Process of improving the dyeing properties of cellulose, cellulose esters and esters by reaction with a carbodiimide compound employing a copper salt catalyst



Unite States Patent "ice PROCESS OF MPROVING THE DYEING PROP- ERTIES OF CELLULOSE, CELLULOSE ESTERS AND ESTERS BY REACTION WITH A CARBODI- IMIDE COMPCUND EMPLOYING A COPPER SALT CATALYST Erich Schmidt, Bad Reichenhall, and Fritz Moosmiiller and Robert Schnegg, Dormagen, Germany, assignors to Farbenfabriken Bayer Aktiengesellschatt, Leverkusen, Germany, a corporation of Germany N Drawing. Application August 16, 1955 Serial No. 528,822

Claims priority, application Germany September 9, 1954 1 Claim. (Cl. 260-231) The present invention relates to a process for improving the properties of cellulose and cellulose derivatives.

The modification of cellulose and cellulose derivatives by contacting the same with reactive organic nitrogen containing compounds has been the subject of extended studies for a considerable period of time. Thus, it has been proposed to modify cellulose by reaction with organic isocyanates, ethyleneimine and also with organic carbodiimides. These prior attempts have found no commercial application since it was found that the hydroxyl group in the cellulose or cellulose derivatives is so unreactive that the excepted nitrogen containing cellulose derivatives were not obtained.

It is therefore an object of the present invention to provide a process by which nitrogen containing cellulose derivatives can be obtained.

A further object is the provision of a process by which such nitrogen containing cellulose derivatives can be obtained in a commercially applicable manner without impairing the desirable properties of the cellulose, such as tensile strength, molecular weight, and the like.

A further object is the provision of a process of animalizing cellulose or regenerated celluloses in filamentary form which renders it possible to dye the fibers or filaments with acid dyestuffs.

A further object is the provision of fibers or filaments from cellulose or cellulose derivatives which contain nitrogen and which can be fastly dyed with simple wool dyestuffs.

Further objects will become apparent as the specification proceeds.

It was found that natural or regenerated cellulose, cellulose esters and cellulose ethers, which still contain free hydroxyl groups, can be reacted even at room temperature with carbodiimides to yield pseudo urea ethers by carrying out the reaction in the presence of catalytical amounts of copper salts.

The reaction is preferably carried out by combining both components in a homogeneous or heterogeneous phase and adding the catalyst. Native or regenerated celluloses are best previously impregnated with the copper compound and the carbodiimide is then caused to act thereon. The addition of catalyst in amount of A to i mol per mol of carbodiimide is sufiicient. In most cases the reaction already proceeds at normal temperature. By raising the temperature of the reaction mixture an acceleration of the speed of reaction may be achieved. The reaction can be carried out in the absence or presence of an indifferent solvent or diluent.

All natural celluloses, like cotton, cotton linters, cellulose pulp and all regenerated celluloses, like regenerated cellulose from viscose or cuprammonia solution can be employed as starting material. The celluloses may be- Patented Sept. 29, 1 959 present in the form of their solutions, as fibers, filaments, yarns or as fabrics.

As cellulose derivatives all cellulose esters and cellulose ethers, like nitrocellulose, cellulose acetate and methylcellulose, may be employed if they still contain free hydroxyl groups.

The following carbodiimides are enumerated as examples: diisopropyl-carbodiimide, n-butylcyclohexyl-carbodiimide, dicyclohexyl-carbodiimide, methyl-tert-butyl-carbodiimide, tert-butylcyclohexyl-carbodiimide, cyclohexyl phenyl-carbodiimide, tert-butyl-phenyl-carbodiimide and diphenyl-carbodiimide.

Shaped objects obtained from cellulose esters or' cellulose ethers after reaction with the carbodiimides may easily be dyed with acid dyestuffs. The fastness of the dyeings obtained is good.

The natural or regenerated celluloses reacted with carbodiimides may also be dyed fastly with acid dyestuffs. By suitable selection of the substituents of the carbodi imides further modifications which are fast to washing and dry-cleaning may be obtained, like water repellency, decrease of the degree of swelling or softening of the cellulose.

Example 1 0.5 gram of anhydrous cupric chloride and 10 grams of diisopropyl-carbodiimide are dissolved in 200 cc. of acetone. 40 grams of cotton linters are added. The liquid is entirely absorbed by the fiber. After storing for 27 days at room temperature the linters are pressed dry and extracted for 24 hours with acetone. The linters then possess a nitrogen content of 0.23 percent (corresponding to 1.03 percent of diisopropyl-carbodiimide). The linters thus treated are easily dyed with acid dyestuffs. If the linters are dissolved in cuprammonia solution, precipitated in Water, the copper removed with 2 N-sulfuric acid and Washed with distilled Water the regenerated cellulose has a nearly unchanged nitrogen content and is also easily dyed with acid dyestuffs.

Example 2 270 grams of linters are heated with 360 grams of diisopropyl-carbodiimide, 1 liter of carbon tetrachloride and 5 grams of cuprous chloride with continuous stirring to C. for 72 hours. The linters are pressed dry, extracted in the soxhlet with acetone for 3 hours and then dried at 70 C.

These linters reacted with carbodiimide are dissolved in a cuprammonia solution and spun to copper-rayon according to conventional methods. The copper-rayon then contains 0.20 to 0.30 percent of nitrogen and may be easily dyed with acid dyestuffs.

Example 3 Cotton linters are immersed in dry pyridine over night, pressed dry and the residual pyridine evaporated in vacuo at 50-60" C. The linters are then again immersed in anhydrous pyridine and again dried in vacuo. 2 grams of linters thus treated are heated in a closed vessel with 8 grams of tert.-butyl-phenyl-carbodiirnide and 1-00 millligrams of cuprous chloride at 80 C. for 48 hours. After decopperizing with 6 percent sulfuric acid and extracting for 3 hours with methanol in the soxhlet the linters have a nitrogen content of 0.73 percent and can be easily dyed with acid dyestuffs.

Example 4 0.5 gram of cuprous chloride is dissolved in 10 cc. of pyridine and the solution then diluted with 990 cc. of water. Cellulose pulp is impregnated with this solution and dried at 70 C. 10 grams of impregnated cellulose pulp are heated with 10 grams of methyl-tert.-butyl-car- Example 4 grams of cotton linters are stirred for 20 minutes with 0.1 .gram of cuprous chloride and cc. of carbon tetrachloride. After the addition of 10 cc. of diisopropylcarbodiirnide the reaction mixture is refluxed with continuous stirring for 8 hours. After extracting for 3 hours in the'soxhlet with acetone the linters contain 0.96

percent-of nitrogen and can be easily dyed with acid dyestuffs. The linters are soluble in cuprammonia solution and may be spun therefrom by conventional methods.

Example 6 '4 grams of cellulose staple fiber are stirred for 5 minutes with 50 milligrams of cuprous chloride and 20 cc. of carbon tetrachloride. Thereupon 5 cc. of diphenyl-carbodiimide are added and the reaction mixture refluxed for 6 hours. After extracting for 3 hours in the soxhlet with acetone the reaction product contains about 0.2 percent of nitrogen. It can be dyed with acid dyestuffs and is soluble in cuprammonia solution.

Example 7 4 grams of cellulose staple fiber are stirred for 5 minutes with 0.1 gram of cuprous chloride and 10 cc. of carbon tetrachloride. Then 10 cc. of diisopropyl-carbodiimide are added and with continuous stirring the reaction mixture is refluxed for 8 hours. After extracting for 3 hours with acetone the cellulose staple 'fiber contains about 2 percent of nitrogen and can easily be'dyed' with acid dyestuffs.

Example 8 Hanks of rayon are immersed for 20 minutes at room temperature into a 1 percent aqueous solution of cupric acetate, centrifuged and dried at 70 C. The rayon hanks are then immersed in dii'sopropyl-carbodiimide, bath ratio 1:20, and heated for 6 hours to about 100 C. After extracting for 3 hours with acetone the rayon contains 0.5 percent of nitrogen and can be easily dyed with acid dyestuffs.

Example 9 Example 10 18.45 grams of methyl-tert.-butyl-carbodiimide and 0.01 gram of cupric chloride desiccated in the exsiccator at 50 C. are stirred into 180 grams of a 20 percent solution of cellulose acetate in acetone (acetic acid content 54.2 percent) and the reaction mixture is stored in a closed flask in the therrnothate for 48 hours at 50 C. Then foils are drawntherefrom. After extracting for 2 hours with petroleum ether these foils have a nitrogen content of 2.23 percent.

Example 11 6.63 grams of tert.-butyl-phenyl-carbodiirnide and 0.01 gram of cuprous chloride are stirred into 50 grams of a solution of cellulose acetate in acetone (acetic acid content 54.2 percent). After storing for 10 days at room temperature a cellulose acetate is obtained which, after extracting for 2 hours with petroleum ether in the soxhlet has a nitrogen content of 0.8 percent.

Example 12 3.09 grams of diisopropyl-carbodiimide and 0.01 gram of cupric acetate, dissolved in 1 cc. of pyridine are stirred into 50 grams of a 20 percent solution of cellulose acetate in acetone (acetic acid content 54.2 percent). After "storing for 14 days the reaction product is precipitated with distilled water. The fibrous precipitate is filtered by suction, dried at 70 C., extracted for 2 hours in the soxhlet with petroleum ether and then contains 0.74 percent of nitrogen.

Example 13 4.80 grams of diisopropyl-carbodiirnide and 0.01 gram of cuprous chloride are stirred into 50 grams of a 20 percent solution of cellulose acetate in acetone (acetic acid content 54.2 percent) and the reaction mixture is refluxed for 6 hours. The reaction product is precipitated in Water, filtered by suction, dried at 60 G, extracted for 2 hours in the soxhlet with petroleum ether and then contains 0.50 percent of nitrogen.

Example 14 A bank of 10 grams of desized acetate rayon is immersed for 20 minutes in a solution of 1 cc. of pyridine saturated with cupric chloride and 99 cc. of water of 20 C., pressed and dried at 50 C. Then the hank is immersed for 8 days at room temperature in a solution of 25 cc. of diisopropylcarbodiimide in 75 cc. of petroleum ether. It is pressed, dried in the air and extracted for 2 hours in the soxhlet with benzene. Acetate rayon thus treated contains 0.3 percent of nitrogen and can be easily dyed with acid dyestuffs.

Example 15 A 10 grams hank of acetate rayon, prepared with cuprous chloride as in Example 14, is immersed for 8 days in 60 cc. of diisopropyl-carbodiimide, pressed, dried in the air and extracted for 2 hours in the soxhlet with benzene. Acetate rayon thus treated contains 1 percent of nitrogen and can be easily dyed with acid dyestuffs.

If the reaction is carried out at 100 C. instead of at room temperature the acetate rayon has a nitrogen content of 1.36 percent after 2 hours and of 2.32 percent after 8 hours.

Example 16 The solution of 10 grams of alcohol-free collodion cotton in 50-100 cc. of acetone is stirred for about 4 hours after the addition of 1.8 gram of diisopropyl-carbodiirnide and 0.1 gram of cuprous chloride. After 24 hours the collodion cotton is precipitated with water from its solution and washed. It can be dyed with acid wool dyestuffs.

In the foregoing examples the reaction of cellulose or cellulose derivatives with organic carbodiimides has been described mainly using cuprous chloride as a catalyst. Although cuprous chloride as a catalyst is preferred in this reaction other copper salts-whether derived from cuprous oxide or cupric oxidemay be employed. Thus, cuprous chloride may be replaced by cuprous sulfate, cuprous acetate, cupric chloride, cupric acetate, cupric sulfate or any other salt of copper.

The carbodiimides employed in accordance with the present invention are either alkyl or dialkyl carbodiimides, aryl or diaryl carbodiimides, alkyl-aryl carbodiimides or cyclo-alkyl-carbodiimides.

It is to be understood that the invention is not limited to the specific embodiments but includes all modifications and variations falling within the scope thereof as defined in the appended claim.

We claim:

In a process for improving the properties of a cellulose compound having free and reactive hydroxyl groups and which is selected from the group consisting of native cellulose, regenerated cellulose, a cellulose ester and a cellulose ether, the step of contacting said compound With a solution containing (1) a catalytic amount of a copper salt selected from the group consisting of cuprous chloride, cupric chloride, cuprous sulfate, cupric sulfate, and cuprous acetate and (2) an organic carbodiimide selected from the group consisting of diisopropyl-carbodiirnide, n-butyl-cyclohexyl-carbodiimide, dicyclohexylcarbodiimide, methyl-tert-butyl-carbodiimide, tert-butyl- 6 cyclohexyl-carbodiimide, cyclohexyl-phenyl-carbodiimide, tert butyl phenyl carbodiirnide and diphenyl carbodiirnide, said reaction being conducted at a temperature up to about 100 C. until an animalized product is obtained which is dyeable with acid dyestuffs.

References Cited in the file of this patent UNITED STATES PATENTS 2,263,730 Hentrich Nov. 25, 1941 FOREIGN PATENTS 511,536 Great Britain Aug. 21, 1939 

1. IN A PROCESS FOR IMPROVING THE PROPERTIES OF A CELLULOSE COMPOUND HAVING FREE AND REACTIVE HYDROXYL GROUPS AND WHICH IS SELECTED FROM THE GROUP CONSISTING OF NATIVE CELLULOSE, REGENERATED CELLULOSE, A CELLULOSE ESTER AND A CELLULOSE ETHER, THE STSEP OF CONTACTING SAID COMPOUND WITH A SOLUTION CONTAINING (1) A CATALYTIC AMOUNT OF A COPPER SALT SELECTED FROM THE GROUP CONSISTING OF CUPROUS CHLORIDE, CUPRIC CHLORIDE, CUPROUS SULFATE, CUPRIC SULFATE, AND CUPROUS ACETATE AND (2) AN ORGANIC CARBODIMIDE SELECTED FROM THE GROUP CONSISTING OF DISOPROPYL-CARBODIIMIDE, N-BUTYL-CYCLOHEXYL-CARBODIIMIDE, DICYCLOHEXYLCARBODIIMIDE, METHYL-TERT-BUTYL-CARBODIIMIDE, TERT-BUTYCYCLOHEXYL-CARBODIIMIDE, CYCLOHEXYL-PHENYL-CARBODIIMIDE, TERT-BUTYL-PHEMYL-CARBODIIMIDE AND DIPHENYL-CARBODIIMIDE, SAID REACTION BEING CONDUCTED AT A TEMPERATURE UP TO ABOUT 100* C, UNTIL AN ANIMALIZED PRODUCT IS OBTAINED WHICH IS DYEABLE WITH ACID DYESTUFF. 